The instant invention concerns vertical shaft impact crushers and particularly the rotors for same.
In a vertical shaft crusher the material descends from a hopper onto the center of a rotor atop a vertical driven shaft. The material is flung radially outwardly by the rotor through exit "portals" in its periphery against an encircling ring of stationary anvils which shatter the material. Alternately, instead of anvils the material strikes an encircling wall of previously crushed material. In either case obviously the rotor itself is subject to substantial wear. This is particularly true in the case of the "open shoe" type rotors, such as those in U S. Pat. Nos. 3,174,697; 3,606,182; 4,065,063; 4,090,673; and 4,577,806, for instance, which require the shoes and associated parts of the rotor to be replaced at fairly regular intervals, usually an expensive and time-consuming job. Another type of rotor consists of a basic cylindrical rotor weldment and collects the material on some of the most exposed surfaces within the rotor weldment in order to shield those surfaces so far as possible from wear. Examples of that approach are found in U.S. Pat. Nos. 3,346,203; 3,970,257; and 4,690,341. The trailing edges of the exit portals are then made replaceable and of hardened material such as carbide, and the upper and lower inner walls of the rotor weldment as well as its periphery are shielded by replaceable liners, all in order to protect the basic rotor weldment.
Even though the rotor designs of the latter three patents reduce the cost of compensating for wear, further improvements to that end in that type of design are desirable, as is the need to reduce as far as possible the time and effort needed to replace the worn parts. These aims are the principal objects of the present invention.